Illumination systems are critical for many devices including computer displays, televisions and for entertainment purposes. Devices may utilize lighting for practical purposes to provide communication of various events or for aesthetic or decorative purposes. As many devices utilize complex geometries and may incorporate many functional components serving as obstacles such as electronics in printed circuit boards (“PCBs”), directing light to traverse a particular path while avoiding these obstacles becomes a challenging problem. The directing of light along a particular path in such a device may be complicated by practical design requirements, which may require for example a power source such as a battery pack to be placed inside the device or a switch to be positioned in a particular position. All of these functional components may generate obstacles for the desired transmission of light along a particular trajectory.
It is often desirable to provide uniform lighting of a device or object having a particular geometry such as a cylinder. In industrial design, an object may have a particular function that may require other components that may complicate the uniform lighting of an enclosing geometry such as a cylinder. For example, a device may require electronic components for particular functionality. The electronic components may be enclosed in a case having a particular geometry such as a cylindrical geometry. The electronic components or other hardware required for the functioning of the device may create particular challenges for uniform illumination of the enclosing case due to scattering of the light off of the components.
The use of an optical waveguide for the directing of light along a particular trajectory is well known. Optical waveguides may operate by capitalizing on a phenomenon known as total internal reflection wherein the index of refraction of the material forming the waveguide in relationship to the index refraction of a surrounding medium such as air is arranged to achieve a particular critical angle. Light rays arriving at the critical angle or greater at the surface between the two materials are refracted along the boundary.
Methods for uniform illumination of planar flat panel displays such as transreflective liquid crystal displays (“LCDs”) are also known. For example, light emitting diodes (“LEDs”) may be used to produce uniform illumination for liquid crystal displays by converting an LED's output flux distribution to a uniform one with plastic, injection-molded light pipes. In particular, an aspheric light pipe may be used as a wavequide.
The use of smooth sides in a wave guide parallel to the direction of propagation of light but utilizing a diffused exit end with random critical angles to allow a high probability that light rays can escape is also known. In addition, light guides may be bent to go around corners. Wedge light guides having either a planar surface or a curved surface may also be used, the former of which may be utilized to backlight transreflective LCD displays is also known.
However, apparatus for bending light around an obstacle are not well known. And, in particular, the bending of light around an obstacle such as a PCB for illumination of a particular surface geometry such as a cylinder is not known. Thus, there is a need for a method and apparatus for directing light around an obstacle such as electronic components, so that the light may provide maximum illumination of a particular surface geometry such as a cylindrical geometry.